1. Field of the Invention
The present invention relates to new organopolysiloxanes which can be transformed into elastomers by heating without using any vulcanizing agent such as peroxides or irradiation.
2. Description of the Prior Art
Elastic organosiloxane products have heretofore been prepared. Historically, only gums, which were obtained by appropriate treatment of diorganosiloxane materials to which different fillers had been added were used as starting materials (see the French Pat. No. 949,361). Yet these elastomers exhibited poor mechanical properties: a maximum elongation of 300%, and a maximum tensile strength of 4.multidot.3 kg/cm.sup.2. In order to improve the quality of the elastomers and to accelerate the process for their production, vulcanizing agents have been used and reticulation effected (see W. Noll, Chem. and Technology of Silicones, Acad. Press 1968, p. 392).
It is further known (see, B. B. Boonstra et al, Reinforcement of Silicone Rubber by Particulate Silica-Rubber Chemistry and Technology, September/October, 1975, p. 568), that if polysiloxanes which are terminated by hydroxy groups are mixed with a pyrogenic silica, a rapid hardening is to be expected which is caused by reticulation and which renders the products practically unusable. From page 570 of this publication, it is seen that when using an untreated silica, the percentage of the gum which is crosslinked immediately after mixing is very high (83-89%). This percentage can be lessened when pre-treated silica, e.g., silica which is treated with hexamethyl-disilazane, is used, but the mechanical properties of the product are strongly affected by such a treatment.